1. Field of the Invention
The present invention relates to an intersection information supply apparatus which supplies, to a driver of a vehicle approaching an intersection or existing in the intersection, information about another vehicle approaching the intersection
2. Description of the Related Art
Conventionally, to prevent accidents in an intersection, a system informing a driver of a vehicle which is going to turn right or left at the intersection of presence of a two-wheeled vehicle approaching the intersection from an opposite side or running in the left side of the vehicle has been proposed (Japanese Laid-Open Patent Application No.57-117096).
In the system, if a two-wheeled vehicle approaching an intersection is detected, the following processes are carried out. If there is a possibility of a collision between the two-wheeled vehicle and a vehicle which is approaching the intersection to turn left (a left-turn vehicle), a warning signal is transmitted from a transmitter (a main control apparatus) installed on the roadside to the left-turn vehicle. In addition, if there is a possibility of a collision between the two-wheeled vehicle and a vehicle which is approaching the intersection to turn right (a right-turn vehicle), a warning signal is transmitted from the transmitter (the main control apparatus) to the right-turn vehicle. In each of the left-turn vehicle and the right-turn vehicle, a warning (display and/or sound) based on the received warning signal is issued.
According to such a system, a collision between a right-turn vehicle and a two-wheeled vehicle approaching from the opposite side and an accident in which a two-wheeled vehicle is caught under the left-turn vehicle can be prevented.
However, in the system as described above, the warning signal does not include information indicating from which directions right and left-turn vehicles approaching the intersection should receive the warning signal. For example, when right-turn vehicles and left-turn vehicles are simultaneously approaching the intersection on the respective up and down lanes (at least four vehicles), it is not determined which vehicle should receive a warning signal transmitted from the transmitter on the roadside. Thus, in a vehicle approaching the intersection or existing in the intersection, a useless warning may be issued.